1. Field of the Invention
The present invention relates to a companion chip for a microcontroller, and to a method for data processing in such a chip according to Claim 8 and a use of the chip.
2. Description of Related Art
To relieve a microcontroller of today's control systems, a companion chip is often used, which supports the controller in the execution of its tasks. Depending on the purpose of the application of the control system, this requires the subdivision or the partitioning of required functions between the microcontroller and the companion chip. In the engine management of a vehicle, for example, this may be done according to the requirements on speed recording and fuel injection.
A partitioning in a standardized microcontroller and a companion chip may be found, for instance, in the Micronas AutomotivePackage™ multi-chip module (MCM). This module is made up of two parts, the base unit (body unit) and the computing unit (engine unit). The base unit implements the communication with the outside world and contains modules for the programmable voltage supply of the computing unit. The computing unit includes the microcontroller and is adaptable to the application. That being the case, the base unit fulfills the function of an IO (input/output) controller.
In the partitioning of the system for the control system of future control devices of BOSCH, a different procedure is selected. In this instance, partitioning takes place by the specification of mandatory functions of the companion chip, for which mandatory modules for this chip then come about. Speed detection and fuel injection control have already been identified as mandatory functions for the engine control system. Although, partitioning in the current control unit generation of BOSCH is already available in which the PCP (peripheral control processor) and the DMA (direct memory access) are used for low level tasks. In future, though, more functionality is to be transferred to the PCP and later to the companion chip. In particular, this is also necessary since as favorable as possible an interface should be used for the communication between the microcontroller and the chip. Since the latter has a limited bandwidth, as voluminous a signal preprocessing as possible is carried out in the chip, and only a few features are still transmitted between the microcontroller and the chip, for the control algorithms on the microcontroller. Application data for controlling the engine may thus remain on the controller, in order to save storage space on the companion chip and not to increase its cost.
Thus, from the definition of the mandatory functions for the companion chip, a hardware architecture comes about having mandatory modules for the companion chip, which, besides the microprocessor, also implements application-specific hardware for communication with the outside world and for signal processing. However, such a hardware architecture requires the development of an appropriate bus concept, interrupt concept and reset concept which supports this design attempt.